Fracture and microstructural studies on normal and high strength concretes with different types of aggregates

Effects of aggregate type on the mechanical behavior of both normal- and high-strength concretes were investigated under bending and mechanical properties under compression. Basalt, sandstone, Eocene and Devonian crushed limestone coarse aggregates were used in the concrete mixtures. For each coarse aggregate type, normal and high strength concretes were made with the same Portland cement and natural sand. In each concrete class, effective water/cement ratio, grading of aggregate, maximum particle size, and cement content were kept constant. For better understanding of the crack initiation and propagation in concretes with different coarse aggregates, a microstructural examination using optical fluorescence and SEM studies are also presented. The results obtained help to explain how the coarse aggregate type and strength of concrete affect the fracture energy in bending. Good agreement was found between experiments and a three phase composite material model previously proposed.